This research program is designed to investigate mechanisms regulating the expression of programs of differentiation in leukemic cells, employing the Murine Erythroleukemia Cell (MELC) line and human leukemic cells. Specifically, we shall study the nature of differentiation-inducing chemical compounds, their interaction with leukemic cells, the program of differentiation including specific transcription, the processing of primary transcripts and the relationship of HnRNA to mRNA, the stability of differentiation-specific species of mRNA during leukemic cell differentiation, the role of poly A sequences, and the nature of changes at the cell surface which accompany differentiation.